Brief Summary

Bees in the genus Osmia are collectively called mason bees or orchard mason bees because they cap their nests with mud. Mason bees, along with leafcutter bees ( Megachile spp.), make up two main groups in the Megachilidae family. Mason bees are abundant throughout Europe, the Mediterranean basin, southwestern Asia, and western North America. They are also found in eastern North America and eastern Asia, but are less common; these bees are not found in the southern hemisphere.